Solutions of partially neutralized aluminum are known to contain a variety of hydrolytic Al species. The identity and distribution of these various forms depends on the hydrolysis ratio (i.e. the OH:Al molar ratio), the Al precursor and the choice of the reaction condition.
It is known in the art that such a variety of hydrolytic Al species exists and that it is possible to distinguish large aqueous aluminum hydroxide molecules using spectroscopic methods such as 27Al NMR which elucidates the structural environment surrounding Al atoms which are embodied in various forms (Casey W H, “Large Aqueous Aluminum Hydroxide Molecules”, Chem. Rev. 2006, 106 (1), pages 1 to 16.
There are two regions in a 27Al NMR spectrum that represent Al nuclei that are octahedrally coordinated (0 ppm-60 ppm) and tetrahedrally coordinated (60 ppm-85 ppm). The octahedral region is exemplified by the hexa-aqua Al species, i.e. monomeric Al, which resonates sharply near 0 ppm. The tetrahedral region is exemplified by resonance near 62.5 ppm from the Al13 polyhydroxyoxoaluminum cation. Al13 is composed of 12 octahedrally coordinated Al atoms surrounded by one centrally-cited Al atom which is tetrahedrally coordinated. The Al30 polyhydroxyoxoaluminum cation is essentially a dimer of the Al13 polyhydroxyoxoaluminum cation and contains 2 tetrahedrally sited Al atoms which yield a somewhat broad resonance near 70 ppm. Depending on calibration, the above ppm values can vary. The values for these peaks are approximately where the resonance occurs.
Aluminum salts can be used for many different purposes, which include antiperspirants, and water treatment.
It is theorized that compositions with high amounts of Al30 would be more efficacious than compositions with high amounts of Al13 at treating water or reducing perspiration. It would be desirable to have an aluminum chlorohydrate salt having a high level of Al30 to be used as an antiperspirant or for water treatment.